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size of first cell near wall for k-epselon model

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Old   April 30, 2004, 02:46
Default size of first cell near wall for k-epselon model
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mukkarum
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Hi

In a case file when I am using Laminar, solution is going to converge but with turbulent k-epselon standard wall function, solution is not going to converge. For turbulent k-epselon medel we have to have first node within the viscouse sub layer. Anyone may please provide me details of calculating the size of first cell near wall for turbulence model?

Thanks & Regards Mukkarum Hussain

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Old   April 30, 2004, 04:24
Default Re: size of first cell near wall for k-epselon mod
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ap
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You need to respect the condition:

30 < y+ < 60

You can check the value of y+ in the Adapt-> Y+/Y* panel, which also allows you to adapt the grid in order to respect this condition.

Hi

ap
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Old   May 8, 2004, 21:17
Default Re: size of first cell near wall for k-epselon mod
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co2
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if i am using k epsilon with std. wall treatment for low reynolds number flow, to maintain y+ between 30 and 60, the grid becomes too coarse. Is it wrong to use k epsilon with std. wall for low Re flow? (In my case low Re flow is buoyancy driven) -- which turb model will be best?
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Old   May 11, 2004, 04:10
Default Re: size of first cell near wall for k-epselon mod
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ap
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For low Reynolds number you could try the enhanced wall treatment, which requires y+ close to 1.

Hi

ap
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